Luminescent Proteins Enable White LEDs without Inorganic Materials

Photonics.comJan 2016
NUREMBERG, Germany, Jan. 13, 2016 — Packaging luminescent proteins in the form of rubber, a white-producing LED eliminates the need for expensive inorganic materials.

Researchers from the University of Erlangen-Nuremberg created the device, which gives off white light created through blue, green and red rubber layers covering one blue or UV LED. This renders the same effect as with traditional inorganic LEDs but at a lower cost, the researchers said.

Rubber with red, green and blue luminescent proteins used to produce BioLEDs. Courtesy M.D. Weber/University of Erlangen-Nurenberg.
Conventional white LEDs are manufactured using inorganic materials such as cerium and yttrium, which are expensive and difficult to source. Another disadvantage is that they produce a color that is not optimal for eyesight, lacking a red component that can psychologically affect individuals exposed to them for long periods of time, according to the researchers.

In response to these limitations, the team developed a hybrid device, called BioLED, which uses luminescent proteins to convert the blue or UV light emitted by a standard LED into pure white light. Their technique involves introducing luminescent proteins into a polymer matrix to produce the luminescent rubber.

The team said they can combine a blue LED with green and red rubber, or a UV LED with blue, green and red rubber, to emit a pure white light while maintaining the efficiency offered by inorganic LEDs.

Blue and UV LEDs are much cheaper than white LEDs, which are made of expensive and scarce cerium-doped yttrium aluminum garnet (YAG:Ce).

"The BioLEDs are simple to manufacture and their materials are low-cost and biodegradable, meaning that they can easily be recycled and replaced," said researcher Rub&eacuate;n Costa. "[The proteins have] luminescent properties that remain intact during the months of storage under different environmental conditions of light, temperature and humidity."

The team is working on optimizing the material to achieve greater thermal stability and an even longer operating lifetime, as well as optimizing chemical composition of the polymer matrix and investigating proteins that are more resistant to device operating conditions, with the ultimate goal of industrial-scale production.